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Thread: SG-121-H unlimited hydro build.

  1. #1
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    Default SG-121-H unlimited hydro build.

    Hello, its been quite awhile...

    building a 1/8 scale F.E. unlimited hull. RCboat Company's SG121-H.

    I am considering power options.. I have been out of it for a few years so any suggestions are welcome!

    I was thinking- a neu 2215? 8-10 cells? 200 amp esc or more?

    ?

    I think this was the last boat I built...
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  2. #2
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    Welcome back Sandy,

    Most of the 1/8th scale folks are running a Neu 1527 1.5Y on 10S or a 1530 1Y on 8 or 9S. A 200+ amp HV speedo is the norm. If you don't care about the competition scene, the motor choices are almost limitless. Which livery will you be modeling? I am certain it will look as fantastic as all of your previous builds.

    If you need any further assistance, feel free to give me a shout.

    All the best,

    Ray

  3. #3
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    ok, thanks for the info...so to refresh my neu motor memory, 1y produces more rpm than 1.5y? I kinda forgot what that meant...

    here is the ambitious paint scheme-
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  4. #4
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    The 1530 1Y is 1100 rpm per kv=on 8s=32500 rpm with a fairly high amp draw. 1527 1.5Y is 850kv-on 10s=31450 rpm with less amp draw. cooler and more efficient. Most of us use a 1/4" drive cable with a 3/16" step down on the prop.
    Mike McKnight@Thunderboat Graphics should have those graphics available in a few months.
    We are surrounded-that means we can attack in any direction

  5. #5
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    ok, thank you all for the infos! another question is what is the average size packs they run, 4000, 5000?

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    6000mah, if you can get them in. These are Giant Power 6000mah 5s packs in my ML Boatworks '89 Winston Lobster. With Steve's hull, you have to build a watertight box for everything-batteries-motor-scu-Rx, etc. Batteries should go in the bow as far forward as possible. 014.jpg
    We are surrounded-that means we can attack in any direction

  7. #7
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    does anyone have a photo of thier set-up they would like to share? motor, esc, etc...

  8. #8
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    Power plant, Neu 1527 . Hull should be here in a week or so..
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    • File Type: jpg U1.jpg (126.7 KB, 108 views)

  9. #9
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    Hey Catboi, I actually have the exact same hull from Steve and have been on a very long project with it for a very long time now. Im sure I can at the very least provide you with some decent insight on anything you need to know regarding an electric powerplant in this hull.

    For starters, I must say that im actually building the boat to replicate the U-88/U-37 drop sponson hull that Billy Schumacher owns, so this hull as pulled from Steves molds is far from correct in this perspective, and in addition to a few other specific characteristics of the hull that I wasnt keen on (regardless of the full size boat I chose) led me to do a very extensive list of modifcations to make it right.

    Also, in my opinion, Steve implemented a somewhat outdated design philosophy for this style of hull when it comes to the bottom of the hull, and even worse, the hull is EXTREMELY HEAVY. When it was shipped to me, the package was over 15lbs.... I also own a Phil Thomas T5 and I dont remember what that package weighed when I received it, but the bare hull was about 6lbs.... So this led to even more substantial modifications on my part, but in the end, im still satisfied at this point. On a positive note, Steve uses excellent materials and does a good job cleaning up the hull overall before he sends it. The wing mounts are fantastic, quality flotation is already installed in virtually every spot possible, and aside from the underside of the hull as mentioned, the overall aesthetics and scale accuracy of the boat is superb, specifically the front curves and shapes of the boat (im a fickler for sponson shape and cockpit shape, and he really nailed these parts).

    I have a ton of pictures if you need any, starting from the moment I began opening the packaging until now. Heres a picture of the most recent mock-up I did with all the components, except the ESC which ill be placing in a compartment I made on the starboard side of the boat. I should note that in this picture, I had already opened up the radio box area by removing the enclosing wall to make the tub open all the way through the length of the hull...... and then i proceedingly removed virtually all of the tub and floor between the cockpit and rear strut area.....The floor section that runs from the nitro engine mounted blocks he has epoxied into the hull towards the back was 1.25 pounds alone.... Since then ive closed the tub back up with plywood.

    Let me know if you have any other questions, im happy to help if I can. BTW, that motor mount configuration pictured is excellent, you need a narrow setup similar to that for these boats. and as stated already, its absolutely critical that you get the batteries as far foward as possible. Thankfully with this particular hull, the radio box is already big enough to fit a 10s, 5500mah setup as molded.



    BIG BOY HYDROPLANES----My first RC boat and build project to boot: (and more content in my profile gallery!) ---- https://forums.offshoreelectrics.com/...proposed-setup

  10. #10
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    Ok,

    We start with the bare hull as supplied from RC Boat Company... Most of the parts I got from OSE or other sources.


    We Start by dry fitting everything, starting with the batteries. There is enough room to move the packs back and forth about 2 inches so fine tuning the balance should easier this way. I choose to mount the motor mid-ship as to keep the model balanced and driveshaft short. I can always add a few ounces of lead to the nose if needed, but taking weight off would be much harder... this also allows room for the esc to be mid mounted between batteries and motor keeping the power leads as short as possible....
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    Next, I re-made the motor mount rails from scrap 3mm carbon fiber so I could bond them to the floor easier than the alu plates...
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  12. #12
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    Now you can see the layout a bit better, only a slight notch was needed to produce a good fit for the motor, carbon was added to the floor during the layup process.

    I had to close up the battery box area so scrap fiberglass was used to make the filler panels.
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  13. #13
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    The stock brass cooling tubes we replaced with larger stainless steel lines and their position adjusted for F.E. .

    A small carbon back up plate was used for the exits.
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  14. #14
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    Let's move onto some part fitment... the turbine tray was enhanced with carbon fiber and west system epoxy to stiffen it.
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  15. #15
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    I decided to cut the cockpit free and make separate sections of the cowl using carbon bulkheads made from scraps.
    The cockpit is attached separately from the main cowl as per the full size boat. A lot of patience and care used here , more on the cowl later....
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  16. #16
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    Ok,

    Now onto the fins and wings... this is bit involved, they will be attached to the stock mounting tabs which are very clever, using 3mm blind nuts and nylon bolts. I used carbon fiber here again to stiffen and add strength. 4mm carbon tubes add further bracing attached with BVM epoxy.This is superior epoxy I used in all my builds.

    You can see here in the last photo the little 1mm thick carbon squares, this is used to bolster the mounting bolt area to prevent the glass from ripping out in a blow-over. Also, scale spacing is used to space the fins off the deck, they dont touch here about a 3/16 gap is used.

    Important: a slight extra gap is used just about everywhere since this model will be painted with 3 part system using clear coat, so the extra space will be needed.

    Also in photo 2, you can see the 2mm thick carbon band added to mounting tab for blind nuts.
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  17. #17
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    The blind nuts on mounting tab can be seen here more closely in the 1st photo.

    The fin brace tabs were mounted in a scale way using s.s. hardware only.
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  18. #18
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    All of the wings get the same treatment, carbon cloth, carbon spar (tube) and s.s. hardware.
    Plus flotation foam where needed.
    A 1mm thick carbon bulkhead is made for the wing using 3mm blind nuts for attachment points, 2 are used per side, later mounted with
    3mm nylon bolts.
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    Last edited by CatBoi; 09-06-2016 at 01:34 PM.

  19. #19
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    The Canard wing mounting tabs, carbon fiber and flotation foam with alu bracket using carbon back up plate for added strength. later the alu bracket will get shaped more completely.

    More of the fins and wings getting their foam and final assembly.
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    Last edited by CatBoi; 09-06-2016 at 02:39 PM.

  20. #20
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    Briefly, the struts mounted in their final position. Prop strut is scale and mounted even with transom.
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  21. #21
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    Here is the scale strut mounted with countersunk holes...
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  22. #22
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    More on foam in the wings.
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  23. #23
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    The rear compartment bulkhead made from 1mm thick carbon fiber sheet. Here you can also see the 1/8" carbon square tube used to support the turbine tray. Motor is now glued into place on its mount.
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  24. #24
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    The cockpit needs to be rasied to fit the way I am mounting the cowl..the cowl will float slightly over the deck instead of touching it directly. A gasket will prevent chafing. the spacer is used and made from carbon fiber sheet 1mm thick. Here you can also see the cockpit mounting pin... the end of this pin gets taped with the hatch to keep it in. A small fiberglass box seals the area from dripping into battery compartment not shown yet. A carbon tab with brass bushing is glued to canopy to key into this slot an grab the pin... very tight and secure!
    the carbon plate by the pin end, just squares off the hatch area for easier taping.

    Here you can see in the last two photos, the rear cowl mounts with clevis pins and back up plates glued to cowl, the front of the cowl is located with 2mm pins like the front of the cockpit.
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  25. #25
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    More on the back up plates and cowl.

    Also the rear plate for hatch added with turbine tray in place.
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  26. #26
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    The snorkel was made to be removable, yet very strong when mounted. Using 3mm tabs of carbon and spacers, this system is used to mount the snorkel now with 3mm blind nuts and bolts.

    Here you can also see the impression made using packing tape and BVM epoxy to mate the two parts together when mounted... this is a touchy area because it has to look good when no snorkel is in place as well.

    1/64" ply added to main cowl to finish intake. Front mounting pins shown in last photo.
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    Last edited by CatBoi; 09-06-2016 at 06:39 PM.

  27. #27
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    Sandy,
    Impressive workmanship and attention to detail.
    Bob

  28. #28
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    Quote Originally Posted by nichismo View Post
    Hey Catboi, I actually have the exact same hull from Steve and have been on a very long project with it for a very long time now. Im sure I can at the very least provide you with some decent insight on anything you need to know regarding an electric powerplant in this hull.

    For starters, I must say that im actually building the boat to replicate the U-88/U-37 drop sponson hull that Billy Schumacher owns, so this hull as pulled from Steves molds is far from correct in this perspective, and in addition to a few other specific characteristics of the hull that I wasnt keen on (regardless of the full size boat I chose) led me to do a very extensive list of modifcations to make it right.

    Also, in my opinion, Steve implemented a somewhat outdated design philosophy for this style of hull when it comes to the bottom of the hull, and even worse, the hull is EXTREMELY HEAVY. When it was shipped to me, the package was over 15lbs.... I also own a Phil Thomas T5 and I dont remember what that package weighed when I received it, but the bare hull was about 6lbs.... So this led to even more substantial modifications on my part, but in the end, im still satisfied at this point. On a positive note, Steve uses excellent materials and does a good job cleaning up the hull overall before he sends it. The wing mounts are fantastic, quality flotation is already installed in virtually every spot possible, and aside from the underside of the hull as mentioned, the overall aesthetics and scale accuracy of the boat is superb, specifically the front curves and shapes of the boat (im a fickler for sponson shape and cockpit shape, and he really nailed these parts).

    I have a ton of pictures if you need any, starting from the moment I began opening the packaging until now. Heres a picture of the most recent mock-up I did with all the components, except the ESC which ill be placing in a compartment I made on the starboard side of the boat. I should note that in this picture, I had already opened up the radio box area by removing the enclosing wall to make the tub open all the way through the length of the hull...... and then i proceedingly removed virtually all of the tub and floor between the cockpit and rear strut area.....The floor section that runs from the nitro engine mounted blocks he has epoxied into the hull towards the back was 1.25 pounds alone.... Since then ive closed the tub back up with plywood.

    Let me know if you have any other questions, im happy to help if I can. BTW, that motor mount configuration pictured is excellent, you need a narrow setup similar to that for these boats. and as stated already, its absolutely critical that you get the batteries as far foward as possible. Thankfully with this particular hull, the radio box is already big enough to fit a 10s, 5500mah setup as molded.
    ]
    What kv HET motor did you pick?
    Nortavlag Bulc

  29. #29
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    The Turbine exhaust made from sheet alu .019" thick. a crimp holds it together.
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  30. #30
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    Here you can see the 1/4" square carbon tube that makes up the lip of the water tight compartment for motor-esc. Also shown is the 1/8 tube for holding up the turbine tray.
    The motor cover is made from 1mm carbon sheet bent and formed to clear the motor tilt. The tape will now run from the deck to the lid seamlessly for a great seal.
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